Regarding HttpSession

[Swapna latha]

Hi all !
I got confused with set and get attributes in HttpSession interface. Please see the below attached program:

package com.bizedge.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Date;

import javax.servlet.ServletException;// ServletException is an class
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;//HttpSession is an interface

public class DateServlet extends HttpServlet {

  public void doGet(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {

    HttpSession hs = request.getSession(true);
/* getSession() and getSession(boolean create) are in javax.servlet.http.HttpServletRequest interface 
 * HttpSession 	getSession()
          Returns the current session associated with this request, or if the request does not have a session, creates one.
 HttpSession 	getSession(boolean create)
          Returns the current HttpSession associated with this request or, if there is no current session and create is true,
          returns a new session.*/
    response.setContentType("text/html");
    PrintWriter pw = response.getWriter();
    pw.print("<B>");

    Date date = (Date) hs.getAttribute("date");
    if (date != null) {
      pw.print("Last access: " + date + "<br>");
    }

     date = new Date();
    hs.setAttribute("date", date);
    /*void 	setAttribute(java.lang.String name, java.lang.Object value)
          Binds an object to this session, using the name specified.
          setAttribute and getAttribute() are methods in interface HttpSession.
           */
    pw.println("Current date: " + date);
  }
}

Here its working fine but if i change date to date1 in getAttribute its showing error but if i write as
Date date=new Date(); then if i change date to date1 in getAttribute its not showing error . Why so ?

Thanks & Regards
Kori Swapna Latha.

[Eswar Nec]

Hi Latha,

Before you post the java code , use code tag. Because it is used to easy view your code.

[Rob Spoor]

Do you mean if you change line 34 from date = new Date(); to Date date = new Date();? You're then trying to declare a new variable with the same name as an existing variable (the one you declare on line 29).

[Swapna latha]

Date date = (Date) hs.getAttribute("date");  
    if (date != null) {  
      pw.print("Last access: " + date + "<br>");  
    }  
  
     date = new Date();  
    hs.setAttribute("date", date);  
    /*void  setAttribute(java.lang.String name, java.lang.Object value) 
          Binds an object to this session, using the name specified. 
          setAttribute and getAttribute() are methods in interface HttpSession. 
           */  
    pw.println("Current date: " + date);  
  

if i write

Date date1=(Date)hs.getAttribute("date");
if(date1!=null)\{
.........
}
Date date=new Date();
..............
................

this type of code its accepting but if i put

Date date1=(Date)hs.getAttribute("date");
if(date1!=null)\{
.........
}
date=new Date();
..............
................

its giving an error why So ?

[Vijayamoorthi Periasamy]

Date date1=(Date)hs.getAttribute("date");
if(date1!=null)\{
.........
}
date=new Date();
..............
................

its giving an error why So ?

You have created the date1 variable and assigning the session date object to it.

But in the next line you are creating a new date object and assiging to the "date" variable but the variable is not even created.
Try Date date = new Date();